The invention relates to a holder for quartz resonator disks with a bottom plate and two current lead Dins attached in the bottom plate, these pins each being pinched flat into a lug at one free end starting with their exit from the bottom plate, wherein the lug includes a mounting section for retaining a marginal zone of the quartz resonator disk. The invention also concerns a process for the production of holders for quartz resonator disks.
Quartz resonators are utilized for a large number of applications in the fields of telecommunication technology, communication technology and computer technology. These quartz resonators are excited to oscillate by an electrical voltage, their natural oscillation ranging between several kHz to above 100 MHz depending on technical requirements and design.
Since quartz resonators are extremely sensitive components, they must be hermetically encapsulated and also fixed by extremely flexible holders. Hermetic encapsulation is normally provided by a so-called all-glass housing or a metallic housing. The holders are formed by two flexible springs which latter are soldered or welded on the current leads extending in an insulating fashion in glass through a bottom plate.
The following approximation formula applies for the thickness of the quartz disks d as a function of the frequency f, for a wide frequency range of about 0.8 to 20 MHz: EQU 1,600/f (MHz)=d (micron)
It can be seen from this equation that the thickness of the quartz disks decreases with increasing frequency. As a result, the quartz mounts and/or holders for quartz crystals must increase in flexibility with rising working frequency so that effectively preclude damage (for example breakage) of the quartz disk in case of mechanical stress (mechanical shock) of the component is effectively precluded. For this reason, at frequencies of larger than 14 MHz, it is presently possible only to use exclusively welded-on or soldered quartz mounts. Although quartz mounts with a welded-on or soldered-on holder exhibit adequate flexibility, they cannot be produced with sufficient dimensional accuracy. Also, it is impossible to realize the low component heights, demanded in the course of miniaturization, when using welded-on or soldered-on springs.
Such a quartz resonator holder for disk-shaped piezoelectric oscillators, welded to the current lead pins, has been known from DE-OS 20 19 389 (incorporated herein reference), this holder consisting of a ribbon-like strip. In order to attain an improvement in the elastic properties of the holder, the latter is provided with a recess on both sides. However, it has been found that the flexibility of this holder is not as yet sufficient, on account of the relatively small recess, in particular in the direction of motion perpendicular to the quartz disk. Especially in case of quartz disks for more than 14 MHz, the elasticity of this holder is not satisfactory.
Integrated mounts, i.e. quartz mounts produced with the current leads from a single part, wherein the current lead pin is flattened at the top end to receive the quartz and is optionally specially shaped and punched out for mounting the quartz disk, usually cannot be utilized at frequencies above 14 MHz since they do not show adequate flexibility.
These conventional holders have the drawback, in particular, that they can absorb impact and vibration stresses only in the longitudinal direction of the quartz resonator base and diametrically to the marginal zones of the disk, on account of unilateral flat pinching. The mechanical strength of the flattened wire pieces leads to local stresses on the quartz resonator disk and to mechanical damage when the disk is introduced in between two wire sections during assembly and, in particular, in case additional mechanical stresses, such as mechanical shock, impact forces, etc., act on the entire component from the outside.
Integrated quartz mounts have been known from DE-OS 22 39 685 (incorporated herein by reference) wherein the electrical connector pins are shaped to be flat merely at their upper end and are angled approximately in a V-shape. The openings of the V-shaped part are aligned with respect to one another, and the indentations serve for plugging in the quartz disk. This conventional holder likewise lacks adequate flexibility for use at frequencies above 14 MHz. The V-shaped design of the mounting section is not enough for fixing the quartz disk so that the carrier plate must additionally exhibit an elevated portion with a slot-like depression for providing a mount for the edge of the quartz resonator. Since this additional fastening of the quartz disk is not flexible, mechanical stresses lead to damage to the quartz disk.
On the other hand, integrated quartz mounts offer the advantage that the connecting point for current lead-through is defined and can be provided with a narrow dimensional tolerance, and that a substantially smaller height of the component can be realized.